The present invention refers to a single or multiple component cartridge with an exchangeable content package.
The use of disposable cartridges for the packaging and dispensing of single component materials, such as adhesives and sealants, is well known. In order to protect the environment from such disposable, chemically contaminated cartridges and chemical waste, alternatives now exist which use the principles of a plastic or plastic/foil laminate sausage type package replaceable within the cartridge in order to repeatedly reuse cartridge components such as the cylinder and piston.
The use of disposable cartridges and mixing nozzles for the dispensing of multi-component and in particular, two-component reactive chemicals is also well established whereby they form both a package and a metering and mixing system for such materials as epoxies, polyurethanes, silicones, polysulphides and acrylics etc. The design of such metering systems incorporate two pistons within metering cylinders for the relative proportioning of each liquid component. Typical relative volumetric ratios are 1:1, 2:1, 4:1 and 10:1. The maintaining of the accuracy of such metered ratios at any point throughout the discharge of the total cartridge contents through a mixing nozzle is usually very critical.
For instance, with a 407 ml capacity system comprising two metering cylinders, one containing 370 ml of part "A" liquid and the other 37 ml of part "B" liquid, the pressurisation of the liquid within and against the total cartridge internal surface areas at up to 15 bars, must not cause any significant deflection of those surface areas to a degree so as to upset the ratio. The higher the ratio and pressure, the more sensitive this issue becomes. Any such deflection can upset the ratio during initial deflection of the cartridge surface areas at the start of pressure build-up and flow, while holding deflection during flow, and during reduction of pressure and deflection at the cessation of flow. The latter situation causing additional possible random "run on" of the liquids through the mixing nozzle after the flow should have stopped and therefore "off ratio" problems both at that time and when flow is started up again. Also, unlike single component cartridges, two-component cartridges are sensitive to air bubble trap points in their design which affect the ratio accuracy from yet another standpoint.
As with single components, there have been attempts to solve this two-component cartridge disposability problem through the use of a disposable/replaceable collapsible plastic or plastic/foil laminate package in the form of a bag or sausage within a reusable cartridge, as disclosed in PCT Application No. WO-91/07333 and European Application No. 541,972. Such packages are scraped off the wall, folded, collapsed and compacted ahead of the piston while the package membrane is being held and pressed against the cartridge wall by internal liquid pressure. Thus the greater the piston force, the greater the counter-productive force of the liquid holding the package membrane against the wall. This self-defeating force situation consumes substantial energy which, in the case of manually operated drive mechanisms, reduces the limited total amount of manual energy available and results in lower dispensing pressure and flow rates. Also, air may be entrapped within the surrounding areas of the packages within the metering cylinders and the compacting of the disposable packages is imperfect, resulting in a liquid chemical residue.
"State of the art" two-component cartridges which best fulfil the above mentioned conditions are highly rigid cartridges with substantial surface area wall thickness. However, such rigid cartridges cause a disposal problem in terms of greater contaminated plastic material waste and volumetric bulk. Therefore, because of this and a lack of cost effective product recycling, it becomes more and more necessary to package and dispense such systems in the most environmentally friendly manner possible.